Mediterranean Gulls Larus melanocephalus wintering in Spain and Portugal: one population or several?

Carles Carboneras, Raül Aymí, Albert Cama, Camille Duponcheel, Joan Ferrer, Renaud Flamant, Salvador Garcia, Jorge Garzon, Antonio Gutierrez, Marc Olive, M.J.M. Poot

Research output: Contribution to journalArticleProfessional

Abstract

Mediterranean Gulls Larus melanocephalus originating from severalbreeding populations (Atlantic, Mediterranean and Black Sea) concur in a few well-known wintering areas in Spain and Portugal. By analysing the records of individuals marked with colour rings, we investigated the connections between the wintering populations occurring in 7 sites distributed around the Iberian peninsula in order to determine the similarities between them. Our observations totalled 1125 individuals in 7 sites (range 44-474) and comprised the whole of the winter season, plus both migration periods. We carried all-time agglomerative hierarchical clustering analysis forthe data corresponding to the seasons between 2005-06 and 2008-09 and plotted the results in a dendrogram; additionally, we compared the lists of individuals recorded ateach site and calculated a coefficient of similarity between pairs of sites. Our findings reveal the existence of 4 clusters, with relatively high exchange ratios of individuals between contiguous sites inside the two main groups: 0,23-0,24 for NE Spain and 0,06for SW Portugal. However, inter-group distance was relatively constant at 0,01-0,02,so the relative spacing of sites did not correspond to the physical distances between them. This effect was most pronounced in Málaga, on the Mediterranean coast ofSpain, and Ares (Galicia), which appeared as independent lines forming part of theAtlantic coast class. The general picture is consistent with a metapopulation structure,each population being independent and only linked to others through dispersal. This conclusion has implications for the conservation of the species, listed in AnnexI of the Birds Directive. Protected areas for this species should be of enough size(to comprise the whole winter range in the Iberian peninsula) and should also be sufficiently representative to be able to afford adequate protection to each independent population.
Original languageEnglish
Pages (from-to)3-11
JournalAiro
Volume20
Publication statusPublished - Oct 2010
Externally publishedYes

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